Halo 3 is a 2007 first-person shooter video game developed by Bungie for the Xbox 360 console. The third installment in the Halo franchise, the game concludes the story arc begun in 2001's Halo: Combat Evolved and continued in 2004's Halo 2. The game was released on September 25, 2007, in Australia, Brazil, India, New Zealand, North America, and Singapore; September 26, 2007, in Europe; and September 27, 2007, in Japan. Halo 3 '​s story centers on the interstellar war between twenty-sixth century humanity and a collection of alien races known as the Covenant. The player assumes the role of the Master Chief, a cybernetically enhanced supersoldier, as he battles the Covenant. The game features vehicles, weapons, and gameplay not present in previous titles of the series, as well as the addition of saved gameplay films, file sharing, and the Forge map editor—a utility which allows the player to perform modifications to multiplayer levels.

Bungie began developing Halo 3 shortly after Halo 2 shipped. The game was officially announced at E3 2006, and its release was preceded by a multiplayer beta open to select players who purchased the Xbox 360 game Crackdown. Microsoft spent $40 million on marketing the game, in an effort to sell more game consoles and broaden the appeal of the game beyond the established Halo fanbase. Marketing included cross-promotions and an alternate reality game.

On the day before its official release, 4.2 million units of Halo 3 were in retail outlets. Halo 3 grossed US$300 million in its first week. More than one million people played Halo 3 on Xbox Live in the first twenty hours. To date, Halo 3 has sold in excess of 14.5 million copies, making it the fifth best selling Xbox 360 game of all time, the second best selling game in the Halo franchise, the best selling Xbox 360 exclusive title and the best selling first person shooter on the console outside of the Call of Duty games. The game was also the best-selling video game of 2007 in the U.S. Overall, the game was very well received by critics, with the Forge and multiplayer offerings singled out as strong features; however some reviewers criticized single-player aspects, especially the plot and campaign layout. A prequel to the game, Halo 3: ODST, was released worldwide on September 22, 2009. A sequel, Halo 4, released on November 6, 2012, was developed by 343 Industries and grossed $220 million on its launch day.

Other Sources of Information
http://en.wikipedia.org/wiki/Halo_(series) https://www.halowaypoint.com/en-us
http://www.halopedia.org/ http://halo.wikia.com/wiki/Main_Page